Flow systems

ABSTRACT

Paper stock flows through a header, a first flat channel, flexible hoses, expansion pipes, pipes of changing cross section, a second flat channel, and a slice nozzle. The nozzle lips are substantially rigid, and conventional sizing across the nozzle orifice is obviated. The structure facilitates ejection of stock from the nozzle in a controlled manner so that the stock remains intact as a wide flat jet a substantial distance beyond the nozzle.

United States Patent [72] lnventors John A. Means Norwalk;

Kenneth B. Latimer, Westport; James Moran, Norwalk; Paul .1. Thoma,Westport, all of Conn.

Jan. 31, 1968 Dec. 21, 1971 Time Incorporated New York, NY.

[21 Appl. No. [22] Filed [45] Patented [73] Assignee 541 now SYSTEMS 3Claims, 4 Drawing Figs.

[56] References Cited UNITED STATES PATENTS 3,309,264 1/1964 Parker eta1. 162/338 X 3,220,919 11/1965 Parker et a1. 162/343 3,328,236 6/1967Burgess, Jr. et a 162/343 X 3,345,254 10/1967 Kilian 162/343 PrimaryExaminer-Reuben Friedman Assistant Examiner-T. A. GrangerAtt0rneyBrumbaugh, Graves, Donohue & Raymond ABSTRACT: Paper stock flowsthrough a header, a first flat channel, flexible hoses, expansion pipes,pipes of changing cross section, a second flat channel, and a slicenozzle. The nozzle lips are substantially rigid, and conventional sizingacross the nozzle orifice is obviated. The structure facilitatesejection of stock from the nozzle in a controlled manner so that thestock remains intact as a wide flat jet a substantial distance beyondthe nozzle.

PATENTEU 00:21 is?! BEZHPW SHEET 1 [1F 2 lltllil i 1 I KENNETH LATIMER.B JAM MORAN &

ATTORNEYS eir PMENTEMEW 3,329,589

SHEET 2 [1F 2 INVENTORS JOHN A. MEANS;

K NETH B. LATIMER, J ES MORAN a PAUL J. THOMA fheir ATTORNEYS BACKGROUNDOF THE INVENTION This invention relates to flow systems and, moreparticularly, to flow systems facilitating ejection of paper stock athigh speed from a nozzle in a controlled manner so that the stockremains intact as a wide flat jet a substantial distance beyond thenozzle and in which conventional sizing of the nozzle is obviated. Theterm paper" is used in a generic sense to include paperboard and otherpaperlike products.

It is essential that a flow system for delivering paper stock to a papermachine wet end be capable of providing a uniform flow of stock frompoint to point across the width of the nozzle and from point to point intime. The stock must also be free of flocculations at the nozzle. To theextend that the flow system fails to meet these requirements, theresulting formed web of paper exhibits imperfections.

In conventional flow systems, the relation of one part to another tendsto be haphazard, and extensive sizing of the nozzle orifices isnecessary in an attempt to achieve uniformity in the formed web.

Conventional apparatus and methods are seriously deficient in a numberof respects. For example, they fail to maintain the proper relationshipof cross-sectional flow areas and flow velocities at various points enroute to the slice or nozzle. Also, the process of sizing the nozzleorifice warps at least one of the lips defining the orifice so that thelips are not uniformly separated from each other at all points acrossthe width of the nozzle. In accordance with conventional apparatus andmethods, the correction of given fiow aberrations at the slice thusinherently requires the introduction of second order flow aberrations.The given flow aberrations and second order flow aberrations do notcancel each other out, and imperfections in the formed web result.

SUMMARY OF THE INVENTION A principal object of the present invention isto remedy the shortcomings of prior art apparatus and methods notedabove. In particular, an object of the invention is to provide a flowsystem facilitating ejection of stock at high speed from a nozzle in acontrolled manner so that the stock remains intact as a wide flat jet asubstantial distance beyond the nozzle. Another object of the inventionis to facilitate the provision of a uniform stock flow from point topoint across the width of the nozzle and from point to point in time. Afurther object of the invention is to obviate conventional sizing of thenozzle orifice.

These and other objects are attained, in a representative embodiment ofthe invention, by the combination of an inlet header, a first fiatsectionconnection to the downstream end i of the inlet header and havingan unobstructed flow channel generally in the shape of a rectangularparallelepiped, and a plurality of hoses connected in a transverse rowto the downstream end of the Hat section. A plurality of expansion pipesis connected in a transverse row respectively to the downstream ends ofthe hoses, Each expansion pipe has a flow channel of increasing crosssection in the direction of stock flow. A plurality of pipes of changingcross section is connected in a transverse row respectively to thedownstream ends of the expansion pipes. Each pipe of changing crosssection has a circular cross section at its upstream end and arectangular cross section at its downstream end. A second flat sectionis connected to the downstream ends of the pipes of changing crosssection. The second fiat section has an unobstructed flow channel in theshape of a rectangular parallelepiped. A nozzle is connected to thedownstream end of the second flat section.

A representative slice nozzle constructed in accordance with theinvention includes first and second lips of great rigidity, each of thelips having a smooth, flat, generally rectangular surface. Means isprovided mounting the lips (a) with the surfaces (i) in spaced-apartrelation to define therebetween a channel for discharging a jet of paperstock and (ii) in an inclined relation with respect to each other todefine a machine direction angle of convergence in the channel. Theangle is constant as a function of machine width and has a value withinthe range of 5 to 10 and preferably about 6.

.The mounting means also mounts the lips (b) adjustably to permitvariation of the angle within the given range and (c) only slightlyadjustable (because of thepreviously mentioned great rigidity) as afunction of machine: width.

In a preferred embodiment of the nozzle, one lip has a first smooth,fiat, generally rectangular surface and the second lip and third smooth,flat, generally rectangular surfaces intersecting each other at anangle. The nozzle lips are mounted so that the first surface on the onehand and the second and third surfaces on the other are in spaced-apartrelation to define therebetween a channel for discharging a jet of paperstock. The surfaces are angularly oriented so that the first and thirdsurfaces are generally parallel and the second surface is upstream ofthe third surface and converges with the first surface in the directionof stock flow.

In both embodiments of the nozzle, conventional sizing of the nozzleorifice by application of varying amounts of force to the lips as afunction of machine width is obviated.

BRIEF DESCRIPTION OF THE DRAWING An understanding of additional aspectsof the invention can be gained from a consideration of the followingdetailed description of representative embodiments of apparatusconstructed in accordance with the invention, in conjunction with theaccompanying drawing, in which:

FIG. 1 is a schematic view in perspective of apparatus constructed inaccordance with the invention;

FIG. 2 is a sectional view in side elevation, on a scale larger thanthat of FIG. 1, showing in greater detail a portion of the apparatus ofFIG. 1;

FIG. 3 is a sectional view in side elevation, on a scale larger thanthat of FIG. 2, of a preferred embodiment of a portion of the apparatusof the invention; and

FIG. 4 is a sectional view in side elevation, on a scale larger thanthat of FIG. 3, of a portion of the apparatus of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a schematic view of aflow system 10 constructed in accordance with the invention. Aconventional side-entering header 12 may be employed for deliveringstock to the flow system 10. The header 12 includes an inlet designatedby an arrow 14, a recirculation exit designated by an arrow 16, and aplurality of flow paths designated by arrows 18 through a plurality oftubes 20.

In operation, a flow of stock generated by a pump or other means (notshown) is continuously delivered to the inlet 14. A portion of the stockflows along paths 18 through the tubes 20 and to the flow system 10, andanother portion of the stock is recirculated through the exit 16. Thisportion of the apparatus is conventional per se, and any other suitablemeans for delivering stock to the fiow system 10 may be employed.

The stock following the paths l8 emanates from the tubes 20 into a flatdistribution channel 22 along paths indicated by arrows 24. Thedistribution channel 22 comprises a lower portion 26 and 28 of thedistribution channel 22 provide flat and unobstructed flow channels forthe stock.

Stock flows through the upper flat channel 28 in the direction indicatedby an arrow 30, and the down stream end 32 of the flat channel 28 isconnected to the upstream ends 34 of a plurality of flexible hoses 36.(For the sake of clarity, some of the flexible hoses are omitted fromthe drawing.)

The downstream ends 38 of the flexible hoses 36 are respectivelyconnected to the upstream ends 4!) of a plurality of expansion pipes 42.The expansion pipes -42 are arranged in a transverse row (with respectto the machine" direction or stock flow direction) corresponding to thetransverse row in which the parallel hoses 36 are arranged.

The downstream ends 44 of the expansion pipes 42 are connected to theupstream ends 46 of pipes 48 of changing cross section. The pipes 48 ofchanging cross section are also disposed in a transverse row and each isconnected to a separate pipe 42.. The pipes 48 of changing cross sectionchange gradually along their length from a circular cross section 50 toa rectangular cross section 52.

The downstream ends 54 of the pipes 48 changing cross section areconnected to the upstream end 56 of a second flat channel 58. The stockflows through the flexible hoses 36, the expansion pipes 42, the pipes48 of changing cross section, and the second flat channel 48, in adirection generally indicated by arrows 60 and 62.

The downstream end 64 of the second flat channel 58 is connected to theupstream end 66 of a nozzle 68. A jet 70 of stock issues from the nozzle68 and is deposited on an endless moving permeable band or between twosuch bands of the wet end of a paper machine for formation of a web ofpaper. The wet end of the paper machine (not shown) transports theinchoate web in a direction indicated generally by an arrow 72.

In accordance with the invention, the relationships of the various partsof the flow system to each other are not haphazard but carefullyprescribed so that the stock entering the nozzle 68 is characterized byuniform flow across the width of the nozzle and needs only to beaccelerated by the nozzle to match the speed of the permeable band orbands on the wet end of the paper machine and, in effect "focused" tomaintain its integrity a substantial distance beyond the slice. Theimportance of maintaining the integrity (i.e., preventing breakup) ofthe ejected stock is especially great at high forming speeds and undercircumstances when because of the construction of the nozzle or of thewet end of the paper machine it is necessary to fly" the stock to adesired point of impact on the permeable band or bands.

For every assumed flow rate at the slice, there are corresponding flowvelocities at various points along the flow system 10. If it is assumedthat the stock flow rate at the nozzle 68 is established at a valuewithin the range of 36 gallons of stock per minute per inch of machinewidth to 40 gallons of stock per minute per inch of machine width, thenthe speed of stock flow through the distributor tubes 20, whichtypically have an internal diameter of three-fourths of and inch,assumes a value between about 15.77 feet per second and about 17.52 feetper second in the apparatus illustrated.

The depth of the lower portion 26 of the distribution channel 22 in adirection normal to the plane defined by the direction of the arrow 30and the cross machine. direction is preferably about 3 inches, so that,for the assumed range of flow rates, the flow speed of the stock in thelower portion 26 of the channel 22 is within the range of about 3.87feet per second to about 4.30 feet per second.

The depth of the upper portion 28 of the channel 22 is preferably about1% inches, and the stock flow speed through this portion of the channelassumes a value between about 7.74 feet per second (in the case wherestock flow rate is 36 gallons per minute per inch of machine width) andabout 8.60 feet per second (in the case where stock flow rate is 40gallons per minute per inch of machine width).

Each flexible hose 36 preferably has an internal diameter of about 1%inches, and the center-to-center separation of the hoses 36 is about 3inches. Each hose should be of an appropriate length, typically 90inches to 110 inches long, or about twice the flow direction length ofthe upper portion 28 of the channel 22. The upper portion 28 may have aflow direction length of 54 inches, for example.

The expansion pipes 42 have an internal diameter of 1% inches at theirupstream ends 40 and expand as cones on an internal diameter of 2 inchesat their downstream ends 44. They are preferably about 24 inches inlength, so that the angle of expansion does not exceed 6.

For the flow rates assumed above, the flow speed decreases from therange of about 19.71 feet per second (in the case of the flow rate of 36gallons per minute per inch of machine width) to about 21.91 feet persecond (in the case of a flow rate of 40 gallons per minute per inch ormachine width) in the flexible hoses 36 and the upstream ends 40 of theexpansion pipes 42 to a range of about 11.09 feet per second to about12.32 feet per second (depending, of course, on the flow rate) at thedownstream ends 44 of the expansion pipes 42.

Like the expansion pipes 42, the pipes 48 of changing cross section arepreferably about 24 inches long, but, unlike the pipes 42, the pipes 48of changing cross section do not provide an increasing cross-sectionalflow area for stock traveling therethrough. On the contrary, thecross-sectional flow area of the downstream ends 54 of the pipes 48 ofchanging cross section is slightly less than the cross-sectional flowarea at the upstream ends 46, so that stock passing through therectangular openings 52 and flowing through the second flat channel 58moves at about 11.61 feet per second to about 12.91 per second,depending upon the flow rate.

The flow direction length of the second flat channel 58 may range up toabout 42 inches, and stock passing therethrough enters the nozzle 68 ofthe invention, important characteristics of a first embodiment of whichare shown in FIG. 2.

As FIG. 2 clearly illustrates, the nozzle 68 is significantly differentfrom conventional nozzles having highly flexible lips. The nozzle 68includes first and second lips and 82 of great rigidity. The lips areformed with smooth flat, generally rectangular surfaces 84 and 86,respectively, and the lips are mounted by means indicated generally at88 with the surfaces 84 and 86 in spaced-apart relation to definetherebetween a channel 90 for receiving and discharging a jet of paperstock.

The surface 84 and 86 are inclined with respect to each other to definea machine direction angle of convergence in the channel 90. The angle ofconvergence is constant as a function of machine width: i.e., the angleis the same at all points across the width of the nozzle 68. The angleof convergence between the surfaces 84 and 86 in the direction of stockflow through the channel 90 is within the range of 5 to 10 andpreferably about 6.

7 1n the embodiment illustrated in FIG. 2, the surface 84 lies in theplane of a surface 92 defining the lower boundary of the flow channelwithin the second flat section 58. The surface 92 is the upper surfaceof a platelike member 94 formed with a flange 96 at the down stream endthereof. A heavy beam 98 is secured by a plurality of bolts such as abolt 100 to the flange 96. The bolt 100 is passed slidably through anaperture 102 in the beam 98 and screwed into a threaded bore 104 formedin the flange 96.

The beam 98 supports the lower lip 80, to which it is securely attachedby a plurality of bolts such as a bolt 106. The bolt 106 is passedslidably through an aperture 108 formed in the beam 98 and screwed intoa threaded bore 110 formed in the lower lip 80. Access to the heads 1 12and 114, respectively, of the bolts 100 and 106 is provided by agenerally prismatic recess 116 formed in the beam 98.

The upper lip 82 is integral with one or more generally cylindricalmembers 118 facilitating pivotal mounting of the lip 82. The member 118is secured by a retaining block 120 formed with a downwardly projectingprotuberance or flange 122. A plate like member 124 similar inconstruction to the platelike member 94 and the surface 126 of which isparallel to and spaced apart from the surface 92 is formed with anupwardly projecting flange 128. At the junction of the member 124 andflange 128, a protuberance 130 is formed having a concave surface 132complemental to the outer surface 134 of the member 1 18. The block 120is also formed with a concave surface 136 extending upwardly andrearwardly (as compared to the direction of stock flow) from theprotuberance 122. The concave surfaces 132 and 136 define a housingwithin which the member 118 is held securely but rotatably. The block120 is secured to the flange 128 by a screw or bolt 138 passed slidablythrough an aperture 140 in the block 120 and screwed into a threadedaperture 142 in the flange 128. The

screw or bolt 138 is provided with a head 144 slotted at 146 andreceivedin a counterbore 148 formed in the block 120. The slot 146 facilitatesthe screwing and unscrewing of the bolt or screw 138.

An adjustment screw 150 and upper and lower adjuster nuts 153 and 154,respectively, facilitate pivotal adjustment of the upper lip 02. Theadjustment screw 150 fits loosely within an aperture 152 formed in arigid beam 155 extending the width of the nozzle 68. The position of theadjustment screw can be adjusted upwardly and downwardly by appropriateadjustment of the adjuster nuts 153 and 154, as those skilled in the artwill understand. Movement upwardly and downwardly of the adjustmentscrew 150 causes movement upwardly or downwardly, as the case may be, ofthe left-hand end (as viewed in FIG. 2) of the upper nozzle lip 32.Specifically, the adjustment screw 150 is connected to the upper lip 102by an anchor pin 160 extending through an aperture 162 formed in theadjustment screw 150. The anchor pin 160 passes through apertures 164and 166 formed in lugs 168 and 169, respectively. The lugs 168 and 169are in turn integral with the upper lip 82. The aperture 162 is largeenough with respect to the diameter of the anchor pin 160 to permitslight play of the anchor pin during pivotal adjustment ofthe upper lip102.

The beam 155 is secured to the flange 120 by a bolt 170 passed slidablythrough an aperture 172 in the beam 155 and screwed into an aperture 174in the flange 120. A recess 176 facilitates access to the adjuster nut153 and the head 170 of the bolt 170.

In the embodiment illustrated in FIG. 2, only the upper nozzle lip 82 ispivotally adjustable, the lower nozzle lip being unadjustably securedwith the surface 84 in the plane of the surface 92. The plane of thesurface 06 intersects the plane of the surface 126 at an angle variablewithin small limits on either side of 6 For example, the angle may be aslittle as or as much as l0".

In certain embodiments (not shown), both the upper lip 02 and the lowerlip 80 are pivotally mounted, and their planes intersect at an anglebisected by a plane parallel to the planes of the surfaces 92 and 126.That is, the plane of the surface 84 is rotated through an angle of,say, 3 clockwise (as seen in FIG. 2) with respect to the planes of thesurfaces 92 and 126, and the surface 86 is rotated through an equalangle counterclockwise with respect to the planes of the surfaces 92 and126 (or clockwise with respect to the plane of the surface 06represented in FIG. 2).

As noted above, the depth of the channel 50 (i.e., the space between thesurfaces 92 and 126) is preferably I inch. The separation of the outerextremities 100 and 182 of the nozzle lips 80 and 82, respectively isthen about one-fourth of an inch, or, more precisely, within the rangeof about 0.220 inch to about 0.280 inch. Thus, there is a reduction incross-sectional flow area of about 4 to I along the flow directionlength (which may be of the order of 6 inches) of the nozzle and acorresponding acceleration of the stock by a factor of about four or sothat the stock ejected from the nozzle is moving at the desired speed(the speed of the paper-forming element or elements on the wet end ofthe paper machine). Slight pivotal adjustment of the type referred toabove facilitates matching the speed of the ejected stock to the speedof the endless forming band on the wet end of the paper machine withoutchanging the pumping capacity of the pumps, which may be adjusted topump stock at an optimum rate, say within the range of 36 gallons perminute to 40 gallons per minute per inch of machine width, regardless,within limits, or the speed at which it is desired to run the wet end ofthe paper machine.

FIGS. 3 and 4 show in detail a preferred embodiment of the nozzle 68 inwhich the lower lip 198 has not merely one but two smooth, fiat,generally rectangular surfaces 200 and 202, respectively, which, withthe smooth, flat, generally rectangular surface 204 of the upper lip 206define the channel 90. The surfaces 200 and 202 intersect at a line 208extending across the nozzle 68 transversely of the direction of stockflow from one side of the nozzle to the other.

The nozzle 60' is connected to a flat channel 50. Stock flows betweensurfaces 210 and 212 of platelike members 214 and 216, respectively. Thesurfaces 210 and 212 are spaced apart from each other by about an inch.A pipe 40 of changing cross section is shown connected to the flatchannel 50' by bolts 210 passed slidably apertures 220 in lugs 222 andscrewed into threaded apertures 224 formed in the platelilte members 214and 216.

The lower lip 190 abuts the platelike member 214 at a line 226 extendingtransversely of the direction of stock flow and tapers upwardly and tothe left (as seen in FIG. 3) from the line 226 to the line 200. Themachine direction length of the lip 198 is preferably about 6 inches,and the machine direction length of the flat" 202 is within the range ofone-fourth of an inch to one-half an inch. A length of nine-thirtiethsof an inch has given excellent results.

The sloping surface 200 thus preferably has a machine direction lengthof 5 /2 inches to 5% inches, and the slope is such that the elevation ofthe flat 202 as compared to the surface 210 (the surfaces 200 and 210being substantially parallel) is about 0.625 inch. Thus, the acutedihedral angle between the plane of the sloping surface 200 and theplane of the surface 210 or 212 is within the range of arc tan0.625/5.75 and are tan 0.625/5.5, or somewhat more than 6.

The angular orientation of the surface 204 of the upper lip 206 isadjustable so that the separation between the flat 202 and the surface204 ranges from a minimum of 0.220 inch to a maximum of 0.375 inch. Whenthe adjustment of the lip 206 is such that the surface 204 is at anelevation (with respect to the flat 202) of 0.375 inch, it is at anelevation of 0.625 inch plus 0.375 inch or 1 inch with respect to thesurface 210 and is parallel to that surface and in the plane of thesurface 212. When the adjustment of the lip 206 is such that the minimumseparation of 0.220 inch exists between that surface and the flat 202,the acute dihedral angle between the plane of the surface 204 and theplane of the surface 210 or 212 is are tan 0.155/13, or less than l.This follows from the fact that the difference between the maximumspacing between the surface 204 and the flat 202 and the minimum spacingbetween those surfaces is 0.155 inch, while the machine direction lengthof the upper nozzle lip 206 is chosen to be about 13 inches.

The acute dihedral angle formed by the plane of the surface 200 and theplane of the surface 204 is equal to the sum of the acute dihedral angleformed by the plane of the surface 200 and the plane of the surface 210or 212 and the acute dihedral angle formed by the plane of the surface204 and the plane of the surface 210 or 212 FIG. 4 shows an adjustmentof the upper lip 206 so that the minimum spacing between the surface 204and the flat surface 202 is 0.250 inch.

The lips 190 and 206 are retained in their desired positions by suitablemounting means. Thus, the lip 190 is secured by a screw 230 passedslidably through an aperture 232 formed in a mounting block 234 andscrewed into a threaded aperture 236. The aperture 236 is spaced apartfrom the end 230 of the lip 190 a distance equal to the distance bywhich the aperture 232 is spaced apart from a shoulder 240 formed on themounting block 234. The end of 230 of the lip 190 thus abuts theshoulder 240 when the screw 230 fastens the lip 190 to the mountingblock 234.

The machine direction length of the mounting block 234 from the shoulder240 to the upstream end 242 thereof is equal to the depth of a recess244 formed in a massive end portion 246 integral with the platelikemember 214. A bolt 240 is passed slidably through an aperture 250 formedin a retaining member 252 and screwed into a threaded aperture 254formed in the portion 246. A hexagonal head 256 facilitates tighteningof the bolt 240.

A shoulder 250 is formed on the mounting block 234 on the side thereofopposite the shoulder 240. The shoulder 250 is adapted to engage acomplemental shoulder 260 formed on the retaining member 252.

The bolt 248 thus urges the shoulder 260 of the retaining member 252firmly into engagement with the shoulder 258 of the mounting block 234,and the mounting block 224 in turn holds the lip 198 so that the end 238thereof firmly abuts the portion 246 and no leakage of stock occurs atthe transverse line 226.

The upper lip 206 is integral at its upstream end 264 with a generallycylindrical member 266. The cylindrical member 266 is retained by aprotuberance 268 formed on a retaining member 270. The surface 272 ofthe retaining member 270 tapers upwardly and rearwardly (with respect tothe direction of stock flow) from the protuberance 268 to itsintersection with the downstream surface 274 of a flange 276 integralwith the platelike member 216.

The surface 274 extends downwardly and forwardly (with respect to thedirection of stock flow) from its intersection with the surface 272, sothat the surfaces 272 and 274 form a housing for the cylindrical member266.

The retaining member 270 is secured to the flange 276 by bolts 278passed slidably through apertures 280 formed in the retaining member 270and threaded into apertures 282 formed in the flange 276.

The downstream end of the retaining member 270 is formed with anaperture 286 through which is slidably passed an adjustment screw 288.The elevation of the adjustment screw is adjustable by adjuster nuts 290and 292. An anchor pin 294 extends through an aperture 296 in theadjustment screw 288 and through an aperture (not shown) in a lug 298.The anchor pin 294 is screwed into a threaded aperture 300 formed in alug 302. The lugs 298 and 302 are integral with a block 304 which is inturn integral with the upper lip 206.

By adjustment of the adjuster nuts 290 and 292, the upper lip 206 can bepivoted about the cylindrical member 266 to adjust the angularorientation of the lip 206.

Those skilled in the art will of course understand that a number ofmounting means such as the cylindrical member 266 and'the various boltsdescribed above may be used across thewidth of the machine in order toprovide a secure mounting for the lips 198 and 206. In all cases,however, the rigidity of the lips is substantially limited to adjustmentof their angle of convergence; substantially no warping of the lipsacross the width thereof.

The flat surface 202 shown in F IG. 4 has been found to contributesignificantly to maintenance of the integrity of the jet beyond thenozzle lips. The pressure drop in the stock at the nozzle occurssubstantially entirely in the portion of the nozzle upstream of thatsurface 202. The pressure drop accompanied by an acceleration occurringin the portion of the nozzle 68' upstream of the flat surface 202 isfollowed by the portion of the nozzle 68' adjacent to the flat surface202, the latter portion acting as a guide to the flow of stock. Thisstructure facilitates the preservation of the integrity of the jet ofstock a maximum distance beyond the nozzle 68 An important advantage ofthe structure is that it permits the introduction of an integral jet ofstock between a pair of forming wires on a paper machine wet end at alocation considerably removed from the nozzle. This permits the use ofbreast rolls having the desired diameters in large paper machines.

The surfaces 84 and 86 of the nozzle 68 and the surfaces 200, 202 and204 of the nozzle 68' should be accurately machined to within oneone-thousandth of an inch within any span of 16 inches. This means that,when the lips are mounted without warping in the flow system, theseparation between the opposed surfaces of the lips defining the flowchannel in a direction transverse of the direction of stock flow isconstant to within two one-thousandths of an inch in any span of 16inches. This is true not only at the downstream end of the nozzle lipsbut also at other positions thereof. Thus, the warping adjustment of theupper nozzle lip (or whichever nozzle lip is adapted to be adjusted)need never exceed two onethousandths of an inch in any span of 16inches. Accurate adjustment within but not exceeding this limit isfacilitated by at the provision of nozzle lips that are substantiallyrigid.

The adjustable nozzle lip is preferably the one the channeldefiningsurface of which lies in the plane or nearly in the plane of one of thechannel-defining surfaces of the flat section. FIG. 3 illustrates thisprinciple. This arrangement assures that the surface 200, whichconverges more sharply with the direction of stock flow than does thesurface 204, need never be adjusted. Such adjustment as may be necessarytherefore causes a minimum disruption of the ejected jet.

In operation, the flow system of the invention is adapted to produce aflow of stock from which it is possible to make paper, including paperof the highest quality, rapidly and economically. The flow system isparticularly adapted for use in combination with modern paper machinesof the type disclosed in an application of John A. Means, Ser. No.407,307, filed Oct. 29, l964, now US. Pat. No. 3,438,854 for l aperManufacture." Stock emanating from the tubes 20 is abruptly deceleratedupon entering the lower portion 26 of the first flat section or channel22 and then accelerated in the upper portion 28. The stock is thenfurther accelerated when it enters the flexible hoses 36 and issimultaneously divided from flow in a single wide sheet to flow in aplurality of flow paths. Then the stock is decelerated as it enters theexpansion pipes 42 and accelerated slightly in the pipes 48 of changingcross section. Simultaneously, flow along the separate flow pathschanges from circular in cross section to rectangular in cross sectionin order to facilitate the reuniting in the second flat section or flatchannel 58 of the flow in a single wide flat stream. Then, in the nozzle68 or 68', the stock is greatly accelerated and ejected at formingspeed.

The alternation of acceleration and deceleration and of flow in a singlewide flat channel and flow in a plurality of separate paths describedabove prevents flocculation and slime growth and maintains the stock ina turbulent homogeneous condition. The stock is then ejected from thenozzle in a controlled manner so that the stock remains intact as a wideflat jet a substantial distance beyond the nozzle.

The requisite rigidity is imparted to the nozzle lips and 82'by makingthem very thick and of a strong material: typically, they may be as muchas 2 inches thick and formed of stainless steel. Thus, adjustment of theadjustment screw and adjuster nuts 153 and 154 shown in FIG. 2 andof-the corresponding structure shown in H6. 2 and of the correspondingstructure shown in FIG. 3 does not warp the upper lip 82 or 206 to thepoint of causing deterioration of the quality of the ejected stock, eventhough a plurality of such adjustment means may be provided across thewidth of the lip. Sizing of the nozzle orifice is therefore greatlysimplified, being largely a matter of matching stock speed to wirespeed, and the results in terms of the quality of the finished productare superior to the results achieved in conventional flow systemsbecause the separation between the outer edges of the lips is uniformacross the width of the nozzle to a degree unrealized heretofore.

The cooperation between the channel 58 and the nozzle 68 or 68' isparticularly noteworthy. The channel 58 establishes the proper velocityfor a papermaking slurry. This controlled velocity is sufficient toprevent flocculation of fibers and at the same time keeps the level ofturbulence low enough to prevent eddies from extending into the formingor dewatering zone of the wet end of the paper machine. Excessiveturbulence results in thin, weak areas in the resulting paper web. Theconvergence, preferably about 6, effected by the nozzle 68 or 68' at theend of the channel 58 imparts a direction to the ejected stock somewhatdifferent from the planes of the surface 84 and 86 or 200, 202, and 204.That is, the flow lines of the ejected stock change direction because ofthe design of the nozzle in such a way as to maintain the ejected stockintact. lt has been found possible to fly the stock of distance of 9 to12 inches between permeable forming bands without degrading the qualityof the completed paper.

The cooperation of the flexible hoses 36 in the combination is also ofparticular importance. In the lengths prescribed, the hoses preventfiber flocculation and break up entering flocks to establishfiber-to-water consistency ratios and flow rates best suited for the wetend of the paper machine.

Thus, there is provided in accordance with the invention novel andhighly effective apparatus and methods facilitating the delivery to apaper machine wet end of paper stock facilitating high-speed andeconomical manufacture of paper of the highest quality. Manymodifications of the disclosure made herein will occur to those skilledin the art. For example, a cross-machine distribution device having atapered, lowvelocity inlet section and a perforated plate can besubstituted for the header 12. Also, a ball-in-socket connection can beused in place of the pins 160 and 294 and associated structure shown inFIGS. 2 and 3. Again, while a generally horizontal orientation has beenillustrated for the flow system 10, other orientations are possible.Accordingly, the invention is to be construed as extending to all of theembodiments thereof within the scope of the appended claims.

We claim:

1. In a slice nozzle for ejecting a jet of paper stock onto the wet endof a paper machine, the combination of first and second lips and meansmounting said lips with a surface of each in nonparallel spaced-apartrelation to a surface of the other to define therebetween a convergingchannel for discharging a jet of paper stock, said surfaces beinginclined with respect to each other to define a machine direction angleof convergence in said channel, said angle being constant as a functionof machine width and having a value within the range of 5 to 10, saidmounting means being adjustable to permit variation of said angle withinsaid range, each of said surfaces being smooth, flat and generallyrectangular further comprising a flat channel upstream of saidconverging channel, formed between two parallel surfaces, said parallelsurfaces forming an angle with at least one of said nonparallelsurfaces.

2. A nozzle is set forth in claim 1 in which said angle is about 6.

3. In a slice nozzle for ejecting a jet of paper stock onto the wet endof a paper machine, the combination of first and second lips said firstlip having a first smooth, flat, generally rectangular surface devoid ofprojections and said second lip having a second smooth, flat, generallyrectangular surface devoid of projections and a third smooth, fiat, saidsecond and third surfaces intersecting each other at an angle, and meansmounting said lips with said first surface on the one hand and saidsecond and third surfaces on the other (i) in spaced-apart relation todefine therebetween a channel for discharging a jet of paper stock and(ii) oriented so that said first and third surfaces are generallyparallel to each other and to the direction of stock flow and saidsecond surface is upstream of said third surface and is nonparallel toand converges with said first surface in the direction of stock flow.

1. In a slice nozzle for ejecting a jet of paper stock onto the wet endof a paper machine, the combination of first and second lips and meansmounting said lips with a surface of each in nonparallel spaced-apartrelation to a surface of the other to define therebetween a convergingchannel for discharging a jet of paper stock, said surfaces beinginclined with respect to each other to define a machine direction angleof convergence in said channel, said angle being constant as a functionof machine width and having a value within the range of 5* to 10*, saidmounting means being adjustable to permit variation of said angle withinsaid range, each of said surfaces being smooth, flat and generallyrectangular further comprising a flat channel upstream of saidconverging channel, formed between two parallel surfaces, said parallelsurfaces forming an angle with at least one of said nonparallelsurfaces.
 2. A nozzle is set forth in claim 1 in which said angle isabout 6*.
 3. In a slice nozzle for ejecting a jet of paper stock ontothe wet end of a paper machine, the combination of first and second lipssaid first lip having a first smooth, flat, generally rectangularsurface devoid of projections and said second lip having a secondsmooth, flat, generally rectangular surface devoid of projections and athird smooth, flat, said second and third surfaces intersecting eachother at an angle, and means mounting said lips with said first surfaceon the one hand and said second and third surfaces on the other (i) inspaced-apart relation to define therebetween a channel for discharging ajet of paper stock and (ii) oriented so that said first and thirdsurfaces are generally parallel to each other and to the direction ofstock flow and said second surface is upstream of said third surface andis nonparallel to and converges with said first surface in the directionof stock flow.